Sophisticated processes have been developed for the production of cellular foamed carbon products. Such processes often involve the use of blowing agents and the application of very high pressures in the fabrication process, and many use highly sophisticated starting materials. These materials, while very lightweight and demonstrating superior strength, tend to be relatively costly, either due to the nature of their starting materials and/or the complexity of their fabrication processes.
There exists a wide and varied class of requirements for low-density materials in the construction, aerospace, transportation, metal processing and other industries for which low-density materials are constantly being developed. Many of these materials exhibit properties such as fire resistance that make them uniquely suited to their end use application. In many applications, however, the aforementioned relatively high cost, low-density materials cannot be used because the final application will simply not justify their relatively high cost.
Feed-stocks to these sophisticated processes for the production of cellular foamed carbon products have included pitches, synthetic polymers, coal extracts, and coals. It is known that commercial pitches commonly have ash contents of less than about 0.5% maximum and for some pitches less than about 0.3% maximum. Synthetic pitches may have ash contents even lower than commercial pitches with values less than 20 ppm being provided by at least one manufacturer. Synthetic polymers would be expected to exhibited ash contents at least as low as those of synthetic pitches, and possibly even lower. Coal extracts have been indirectly taught to have no ash content as the ash component of the extracted coal is directly taught to remain with the non-soluble portion of the extracted coal. Commonly, bituminous coals have ash contents in the about 5% to about 10% range (as determined by ASTM Test Method D 3174, “Ash in the Analysis Sample of coal and Coke”, or other functionally equivalent test method). Coals exhibiting higher ash contents are well-known. Such higher ash contents may be at any value greater than about 10%. Such higher values may be attributed to the inherent properties of the coal and/or to the manner and care with which the coal is mined. Coals having ash contents in the range of about 2% to about 5% are usually available but typically from only a limited number of suppliers at best. Such lower ash values can be attributed to the inherent properties of the coal, careful mining procedures, and/or to readily available coal washing techniques. Coals having ash contents of about 1% to about 2% are known but are relatively uncommon. Coals having ash contents of less than about 1% are relatively rare. Some advanced coal cleaning technologies may have the capability of reducing coal ash contents to less than about 2% but such technologies are not generally in common use and are typically expensive and/or difficult to practice. It should be noted that all percentage ash contents cited in this specification are mass-based.